Effect of Fire on Ant Assemblages in Brazilian Cerrado in Areas containing Vereda Wetlands

Abstract

Cerrado is a biome whose evolution is intimately influenced by constant fire events. Although many species are capable of dealing with this predictable impact, many others may be negatively affected, resulting in community changes after fire. Using ants as bioindicators of changes in biodiversity and environmental conditions, this study evaluated the effects of fire in two Cerrado vegetation types: "cerrado" sensu stricto, a xeric savanna, and wetland "veredas", a mesic vegetation on floodable soils, where water concentrates and ultimately flows towards rivers. We examined the effects of fire on both habitats in two independent sites, but with special consideration to the wetlands, which are not fully adapted to fire. Ant sampling was conducted twice before and twice after a fire event, using 288 baits and 416 pitfall traps (soil and arboreal), and 16 hand collections along three random replicate transects per area. Ant species richness and abundance were resilient to fire, and exhibited a remarkably consistent seasonal variation at unburned and burned sites. On the other hand, the fire markedly changed the ant species composition. In the wetlands, the fire spread underground due to the high concentration of peat. The impact on ant assemblages was substantial and visually perceptible for some species like Camponotus rufipes, which suffered a considerable reduction in the number of individuals after fire in this habitat. In the cerrado, a similar result was observed for Crematogaster nr. obscurata, which disappeared after fire. The wetland vegetation having little adaptation to fire, plus low resilience in the ant community resulted in a severely changed fauna, both in guild predominance and species composition, and return to an original state is uncertain.

The effect of remnant forest on insect successional response in tropical fire-impacted peatland: A bi-taxa comparison

“…This indicates that peat fires have a negligible effect on ant species richness. The insensitivity of ant species richness to fires agrees somewhat with a previous study conducted in the Brazilian Cerrado wetland [45]. It was reasoned that any loss of ant species in a given site can be offset by gains of other generalist ants, so the effect on community composition in association with the ants’ functional roles in an ecosystem is pronounced [45].…”

Assessing Wildfire Regimes in Indigenous Lands of the Brazilian Savannah-Like Cerrado

“…The years with the largest extent of the burned area occurred between an interval of one or two years, a behavior common in Cerrado environments also observed in national parks and other indigenous lands [37,48]. This short return interval can be related to the intrinsic high recovery of grasslands during the rainy season, a physiognomies that predominates the Cerrado formations, which implies a great accumulation of biomass susceptible to fire [54,55].…”

Ant diversity decreases during the dry season: A meta‐analysis of the effects of seasonality on ant richness and abundance

“…From the reviewed studies, few detected effects of climatic seasonality on the diversity and composition of ant assemblages in Brazilian biomes. Some authors found a higher ant richness and abundance in the wet/summer season and differences in species composition between seasons (e.g., Castilho et al, 2011; Costa‐Milanez et al, 2015; Rosado et al, 2013; Santos et al, 2014). To explain these results, the authors suggested the influence of abiotic factors, such as temperature and precipitation, on ant foraging activity (Almeida et al, 2007; Levings, 1983; Nunes et al, 2020).…”

“…Besides, few studies have reported the opposite effect of seasonality on ant assemblages, that is, higher richness and abundance of species in the dry/winter season (Costa-Milanez et al, 2015;Gomes et al, 2014;Marques et al, 2017). One of the common explanations for this pattern is the possible expansion of ant foraging areas due to the reduction in resource availability in the dry/winter season.…”